An example of a flip mobile-phone of this kind has a touch panel that allows a user to perform a sensory input operation by tapping with a finger, a touch pen, etc. and a direction sensor for detecting a relationship between the up and down directions of a first casing and a second casing that are folded with each other, as external sensors. Furthermore, generally prevalent mobile phone apparatuses have a photosensor, etc. for detecting an amount of light outside in order to adjust brightness of a backlight of a liquid crystal display device.
However, in such a mobile phone apparatus and today's mobile phone apparatuses, since a plurality of external sensors are provided, more electric power is required to maintain the operations of the external sensors, so that there is a problem of speeding up consumption of the limited electric power of the battery.